We propose experiments to investigate the effect of food contingent stimuli at preabsorptive and postabsorptive sites on meal size and intermeal interval in normal rats, genetically obese mice (C57BL/6J-ob/ob), ventromedial hypothalamic knife-cut rats of the experiments are designed to determine where food stimuli act to control feeding behavior. The role of pregastric food stimuli are investigated intensively by studying sham-feeding in the chronic gastric fistula rat. On the hypothesis that the obese mouse has a neurological abnormality involving central catecholamine neurons or the neurons which have catecholaminergic receptors, we propose to investigate the anatomy of the central catecholamine systems in the obese mouse using the glyoxylic acid histofluorescent technique.